Carbon is carbon, but water is not water and land is not land

Besides the ecological footprint you might also have heard of the carbon footprint and the water footprint. Only carbon footprint makes sense; I criticized ecological footprint in an earlier post, but I did not mention another problem that also holds for water footprint.

Why do I think carbon footprint makes sense? It’s about one environmental problem: climate change. It’s about one type of pollutant, greenhouse gases such as carbon dioxide and methane, and it doesn’t matter where you emit them. Whether you burn coal in Las Vegas, Shanghai, or Maasbree: the radiative forcing of the greenhouse gases you emit is similar.

How different that is with water. Growing fairly thirsty crops in Las Vegas is a much bigger problem than growing very thirsty crops in Maasbree, simply because there is much more water in the Dutch province of Limburg than in the American state of Nevada. In Nevada you would have to extract groundwater to irrigate your crops, and you would have to extract a lot of it because a big part of what you spray on your crops will evaporate before your crops can drink it. The groundwater aquifers you extract your water from will take a very long time to be replenished. In Limburg, on the other hand, you can use water from the Meuse (which is what Maasbree is named after), and even if you extract groundwater there is plenty of rain and river water to replenish it. Nevertheless, the water footprint will simply look at water use or the thirstiness of your crops, so growing very thirsty crops in areas where there is plenty of water is worse than growing somewhat less thirsty crops in areas where water is very scarce. Water depletion is a local problem: you can’t compare Dutch water to Nevadan water. This problem does not hold for greenhouse gas because a Dutch ton of CO2 has the same effect as a Nevadan ton of CO2.

Ecological footprint has the same problem. Here the unit is not tons of carbon or liters of water, but hectares of land. With land it is important to consider the opportunity cost: if, say, you would use it to store carbon, what uses of the land would you have to forgo? In other words: if you would not use it to store carbon, what else would you have done with it? And then it turns out that it actually matters a lot whether we are talking about highly productive land in a well-drained and fertile Dutch polder or some remote wasteland with no biodiversity to speak of. Ecological footprint aggregates all land used by a person, a city, or a product, including the hypothetical hectares one would need to store carbon. Whether it is office space in the centre of Hong Kong, a highly diverse rainforest in Brazil, the fertile polder of Het Groene Hart or the barren desert of the Sahara: land is land, according to the ecological footprint. But it isn’t, just like water is not water.

Granted: bad arguments against ecological footprint

While writing my post on Ecological Footprint I came across a lot of sound arguments against it, but, to be fair, also a few less convincing ones. Here are two that hold more than a grain of truth, but simply will not convince the EF’s proponents.

“Land prices will stop you from sequestering carbon”
The argument goes like this: it’s unrealistic to assume all carbon emissions are mitigated by planting trees, because as more and more land is covered by ‘carbon farms’ (yes, not only the term exists, so does the practice), land will become so expensive that you will resort to other ways of climate change mitigation.

Of course you would expect land prices aree extremely high when the last square meter of agricultural land is converted to a carbon farm: after all, we only have one planet. But perhaps that is exactly what EF tries to tell us? Nevertheless, the argument points towards another problem with EF: it assumes sequestration is the only way to deal with GHG emissions, or at least the cheapest way. But although adaptation to climate change has long been a dirty word in the climate debate, it would be bad science and bad policy to dismiss it straight away – especially if sequestering carbon becomes prohibitively expensive. Given the choice between starvation and building better coastal defenses, my motto would certainly not be let em eat tree bark.

“You can overshoot temporarily without wrecking the planet”
EF counts any policy that increases stocks of carbon as unsustainable, but it is possible to accept a slight, temporary increase in carbon stocks without inflicting major damage to the climate system. Indeed, it might even be optimal to do so. If we could eradicate poverty by a temporary spurt in economic output to build up capital (read: build machines, infrastructure, establish institutions, etc), after which we close biophysical cycles again, bringing our impact on the planet within safe boundaries, the elevation to a higher but sustainable standard of living may more than offset the temporary damage inflicted on the environment.

But to me this sounds too much like the drunk who is caught by police while starting his car and tries defending himself with the excuse that he wasn’t planning on actually driving it. Are you really trying to tell me that flying to distant holiday destinations several times a year (just to name an example) is supposed to be temporary, and to help developing countries get richer? Don’t get me wrong here: I think everybody is free to take a long vacation on the other side of the globe if he or she likes, although we should do so facing prices that convey all relevant costs, and that includes our impact on the environment. But most people would assume that our current way of life is at least supposed to be maintained indefinitely, and otherwise to be expanded. The EF’s proponents argue that this is impossible. There may be a lot to be said against their position, but claiming it’s all meant to be temporary is not one of them.

The Living Planet Report (2): Ecological Footprint makes for nice reading but abominable science

WWF’s latest Living Planet Report presents a bleak picture, some hopeful trends, an awfully bad indicator and lots of pious words on sustainable development.

Oh boy: the Ecological Footprint

NGOs like WWF love indicators like the Ecological Footprint. Its message seems simple: if we want to continue living the way we do now, we need more planets to offset all the bad thing we do. Alas, it is one of the worst concoctions that ever came out of an econophobic environmentalist’s imagination. At best it tells us things we already know. At worst it suggests policies that are harmful to people AND the environment. It is claptrap. Trash. Ecological Footprint is evil. The objections are legion, but the main ones are:

  • EF tells us nothing about how “bad” or how “serious” impacts are;
  • It depends strongly on carbon emissions and makes wildly strong assumptions on how carbon emissions are mitigated;
  • It is biased against cities and trade.

Ecological Footprint does not tell us how bad impacts are

Suppose we have two pollutants. One will, if it reaches a certain concentration, kill all life on the planet. Theoretically we can reduce its concentration with some technology that takes very little space, but because we think it is too expensive we haven’t installed it yet. (Let’s say we can install some device on the North Pole that sucks the pollutant out of the air.) The other pollutant causes a nasty rash among a small share of the population. Reducing its concentration requires the planting of huge areas of forest, but we can use these forests also for recreation, timber, and all other kinds of uses. Which pollutant should be banned?

EF would say: ban the second pollutant. Not because that pollutant causes a rash, not because EF aims to kill all life on the planet, but because mitigating that pollutant’s emissions takes more hectares than mitigating the first pollutant. So one problem with EF is that it ignores how a given activity affects our well-being, or that of future generations. All that matters is how far we are from a steady state, and this “how far” is measured in hectares. Why hectares? Are they such good indicators of the well-being of humans, or life on Earth in general? No. But it gives you pretty pictures: you can show your readers a picture of Earth besides one or two other planets and tell people we also need the other planets. And then your readers can say: “Oh no! We need two more!” It’s a great propaganda tool.

Ecological Footprint depends strongly on carbon emissions

In fact, EF ignores toxic substances altogether, because, you guessed it, they are so difficult to translate into hectares. The only exception is carbon emissions: after all, we could in theory plant trees to absorb and store carbon. (Please don’t start now that carbon is not a pollutant but plant food, and that anthropogenic global warming is a leftist conspiracy to take away your SUV. Conspiracy theories give me a rash.) This is what the EF assumes: that we need to grow trees in order to absorb all the carbon we emit. No wonder carbon makes up about 50% of the global Ecological Footprint! In case you haven’t noticed: the fact that 50% of the EF is caused by carbon emissions is not the result of the gravity of human-induced climate change (which I agree is serious), but of the assumptions that the EF makes on how we should mitigate those emissions (which may be or may not be realistic but is in NO way related to the consequences of human-induced climate change). Moreover, there are many ways of mitigating carbon emissions, many of which take less space than planting trees: Carbon Capture and Storage, for instance.

Ecological Footprint is biased against cities and trade

If the LPR simply presented the EF as an indicator of whether we can keep up current consumption rates indefinitely or not, it may not necessarily be wrong, although it would be useless: we already know from IPCC, IUCN, and other bodies that we are having impacts that are drastically altering ecosystems, and are likely to limit future generations’ well-being. The problem so far seems to be that it is presented as a quantitative measure of how bad things are, which it is not. However, the LPR (as well as the EF’s proponents) go further than that: they claim cities are evil, and they base that claim on cities’ Ecological Footprint.

The reasoning is like this. Imagine a city that covers 100 km2. Of course it cannot exist on its own: after all, it is a city, population density is high, so it is impossible to feed all the city folk by growing food on the mere 100 km2 covered by that city. So it buys food from the rural areas around it. The inventors of EF claim this is a bad thing. Our imaginary city could have an ecological footprint several times its physical surface area, because all that farmland provides food to the city. So according to EF’s proponents it is unsustainable, and should reduce its footprint to something more in line with its physical size. Cities are parasites on their surroundings, the EF folks claim.

This ‘parasitism’ is nothing more than trade. A farm’s footprint is smaller than its physical area because it only uses a fraction of the food it produces: the rest is sold, mainly to city folk. This is good: farmers can specialize in farming, city folk can specialize in activities for which it pays to be close to other people, such as trade, banking, research, and education. Throughout history, cities have been hotbeds of innovation, of revolution, of new ideas being spawned, spreading, and finding fertile ground.

No wonder EF is also biased against international trade: densely populated countries (read: countries where land is in short supply) like Singapore and The Netherlands import a lot of food and timber from countries that have lots of land. This way everybody can do what he or she is best at. Really, you don’t want to live in a world where everybody grows his own food, fetches his own water, generates his own energy, builds his own house, and pulls his own teeth. Trade enables division of labour, which enables us to do a lot more with the same resources.

Better indicators? Prices!

If EF is so bad, is there any other way to express the state of the world’s environment in one figure? The short answer is: no. The issues are too diverse, and too numerous to be translated in a single figure. The long answer: what should such an indicator reflect? At least it should reflect how serious the issues are, because policy makers will set their priorities with the help of the indicator. Prices may be imperfect reflections of what people want, but they are still way better than an arbitrary variable like surface area. (Why not Joules? Or grams? I know: less pretty pictures.) The indicator should also reflect not only our current happiness, but also our impact on the future. So a country that throws a big party squandering its natural resources should have a lower value than a country that uses the same amount of resources more wisely. The first issue is not in EF, and the second issue only partially (and using, as I said, a poorly suited unit). Gross National Income, which is widely used by economists but also criticized by ecologists, is also a very poor indicator of wealth, mainly because it ignores natural resource depletion. But there are better, less well-known indicators: the latest edition of The World Bank’s Little Green Data Book presents not only Gross National Income of different countries and regions, but also their Adjusted Net National Income, which is GNI minus consumption of fixed capital, and depletion of energy resources, minerals, and forests. And thankfully, the word “footprint” is nowhere to be found.

WWF’s Living Planet Report

WWF has a new edition of its Living Planet Report out. I promise to read it more carefully in the near future, but what bothers me about it already is their use of the ecological footprint to make their case. Economists have long criticized the use of the EF as a measure of sustainability. I’ll get deeper into the reasons for that in future posts, but the bottom line for me is that it is often interpreted in a normative sense, even though it cannot be used for that purpose. In other words: it only tells you, in a simplified way, whether we can keep up our current way of life, but it says nothing about the consequences of living unsustainable. Therefore, you risk sounding the wrong alarm bells. By the same token, the way it is designed it is strongly biased against cities and trade: two things economists like and ecologists dislike. This goes some way in explaining its popularity but that does not mean it is an accurate indicator.

Anyway, I’ll go deeper into this later.

Edited 13 June 2012: Changed the title. I should have known about the kind of connotations animal limbs can have (pandas, camels). That’s what you get when you’re not a native speaker.